Toy stethoscope with electronically simulated heartbeat



March 13, 1962 H. E. BARNETT 3,024,568

TOY STETHOSCOPE WITH ELECTRONICALLY SIMULATED HEARTBEAT Filed March 9, 1960 I FIG. I

l M 26 F 12 R4 R-Z L m/ gm Jl 04v" ATTYS United States atent 3,024,568 Patented Mar. 13, 1962 ace 3,024,568 TOY STETHOSQOPE WITH ELECTRGNICALLY SIMULATED HEARTBEAT Harry E. Barnett, 6841 S. Constance, Chicago, iii. Filed Mar. 9, 1960, Ser. No. 13,803 7 Claims. (Cl. 46232) This invention relates generally to toys and more particularly to educational toys in the fields of medicine and human anatomy. More specifically, the invention relates to a toy stethoscope which, when pressed to the chest of a doll or the like, realistically simulates a human heartbeat.

In recent years, there has been a great trend to make childrens toys appear ever more realistic and life-like. Thus, for example, we now have dolls which perform numerous human functions such as crying, drinkin wetting, etc. Similarly, there have been provided educational toys such as doctors or nurses kits containing -authentic syringes, thermometers, bandages, splints and other medical instruments and devices. There have even been introduced dolls capable of simulating various symptoms. Of course, playing doctor or nurse with the aid of such toys is not only a favorite pasttime, but it is likewise highly educational in acquaintaining children with some of the basic facts of first aid, human anatomy and medicine.

The most essential of all human organs is of course the heart. It is well known that the medical profession employs numerous instruments for diagnosing the heart by listening to the heartbeat in order to determine the condition thereof. Similarly, there have been provided toy Stethoscopes which enable the user to listen to an actual human heart beat. However, to the applicants knowledge, there has not yet been provided a toy which simulates the human heartbeat so that the young play doctor or nurse may use the same to impart life to an inanimate doll or the like.

It is therefore an important object of this invention to provide a toy stethoscope having means which simulates the human heart beat so that the user may listen thereto whenever desired.

The physical abuse to which the average toy is normally subjected is well known. Thus, where the toy is constructed of ordinary mechanical elements, the operational life of such a toy is usually extremely short. This is particularly true where the operation of the toy involves a number of moving mechanical parts.

It is therefore another important object of the invention to afford a toy stethoscope of the character described in which the means for simulating the heartbeat is electronically operated, thereby eliminating moving mechanical parts. In this regard, the invention employs a pair of transistors in the sound producing circuit so that the toy is capable of even longer life than might be expected.

A further object is to provide a toy stethoscope in which the electronic sound producing means is very compact so that the same way be readily self-contained in a stethoscope head of substantially normal size. A related object is to so construct the toy stethoscope that said sound-producing circuit is activated by a concealed switch positioned on the head of the stethoscope. Thus, the stethoscope head may be activated by pressing it against an object, such as a doll, whereupon the user automatically hears the heartbeat.

Still another object is to afford a toy stethoscope in which said sound producing means simulates a heartbeat of normal frequency; viz, approximately 72 beats per minute.

Yet another object is to provide a toy stethoscope which simulates a most realistic heartbeat in that each beat has the well known double sound.

Still a further object is to afford a toy stethoscope of the character described which is inexpensive to maintain in that the same employs an ordinary replaceable flashlight type dry-cell battery as a source of electrical power.

Yet a further object is to provide a toy stethoscope of the character described which may be inexpensively fabricated and yet is most durable, amusing and educational.

With the foregoing and other objects in view which will appear as the description proceeds, the invention consists of certain novel features of construction, arrangement and a combination of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the form, proportion, size and minor details of the structure may be made without departing from the spirit or sacrificing any of the advantages of the invention.

For the purpose of facilitating an understanding of my invention, I have illustrated in the accompanying drawings a preferred embodiment thereof, from an inspection of which, when considered in connection with the following description, my invention, its mode of construction, assembly and operation, and many of its advantages should be readily understood and appreciated.

Referring to the drawings in which the same characters of reference are employed to indicate corresponding or similar parts throughout the several figures of the drawings:

FIG. 1 is a circuit diagram of the heartbeat simulating electronic means of the invention; and

FIG. 2 is an enlarged fragmentary view, partially in section and partially in elevation, showing a typical embodiment of the invention and the manner in which the heartbeat simulating means may be positioned therein.

Referring now to FIG. 1 of the drawings, the circuit shown is designated generally by the reference character 10 and includes a switch 12 and a power source such as a battery 14.

In general, the circuit 10 comprises a form of transistor multivibrator in which two transistors, TRl and TR2, are energized by the battery 14. The transistor TRI has a base 16 and collector 18 connected to the positive terminal of the battery 14 through a pair of bias resistors R-1 and R-2 respectively. The transistor TRl also comprises an emitter 20 which is connected to the negative terminal of the battery 14.

Similarly, the transistor TR2 comprises a base 22 which is connected to the positive terminal of the battery 14 through a bias resistor R-3 and a collector 24 connected to said battery terminal through the coil 26 of a transducer indicated generally by the reference numeral 28. The transducer 28 may be any of the common types incorporating a diaphragm therein. The transistor TR2 includes an emitter 30 which is connected to the negative terminal of the battery 14.

A condenser 0-1 is connected between the base 16 of the transistor TR1 and the collector 24 of the transistor TR2. Similarly, a condenser C-2 is connected between the collector 18 of the transistor TRl and the base 22 of the transistor TR2. It will be understood, of course, that while the transistors TRl and TR2. are shown as the N-P-N type, transistors of the other types may likewise be employed with equally satisfactory results.

In theory, the circuit operates as follows:

When the switch 12 is closed, the potential of the battery 14 is momentarily applied to both transistors, TR1 and TR2. At that instant, some current tends to flow through the transistors TR1 and TR2. Simultaneously, the condensers C-1 and C2 are being charged. Thus, for example, the initial surge of current through condenser C1 rapidly lowers the potential of the base 16 of transistor TR1 into cut-off so that said transistor becomes non-conducting.

With the transistor TR1 being in a state of non-conductance, the transistor TR2 now assumes substantially the full potential of the battery 14. Thus, transistor TR2 is now fully conducting. At the same time, the condenser C1 is also charged to substantially the full potential of the battery 14. This charge on the condenser C-l is sufficient to keep transistor TR1 non-conducting as long as the potential at the base 16 is maintained below the cut-off value.

However, the condenser Cl begins to discharge through the resistor R-3 and the coil 26. When the potential at the base 22 of transistor TR2 has been lowered below the cut-off value, that transistor becomes non-conducting. At this time, the transistor TR1 assumes substantially the full potential of the battery 14 and becomes fully conducting. Simultaneously, the condenser C-2 acts to maintain transistor TR2 in cut-off condition until its potential is discharged through resistors R-1 and R-2, at which time transistor TR1 is once again rendered non-conducting.

It will be noted from the foregoing theoretical explanation that the circuit 10 assumes a condition of stable oscillation. Each cycle of operation results in the generation of a switching pulse which is substantially rectangular in configuration. As each pulse passes through the coil 26, the transducer 28 converts the same into sound energy. Since each electrical pulse is quite transient in nature, the diaphragm of the transducer 28 quick- 1y plops back to its original position prior to deflection by the pulse. The transducer 28 thus produces a double sound for each electrical pulse which most realistically simulates the human heartbeat.

The frequency of oscillation of the circuit 10 is of course determined by the RC constants of the condensers C-1 and C2 and the respective resistances through which said condensers discharge. I have thus chosen values for these components which cause the circuit 10 to oscillate at the frequency of approximately 72 cycles per minute, which is equivalent to an average human heartbeat frequency.

Referring now to FIG. 2 of the drawings, my improved toy stethoscope with the circuit 10 included therein is shown and indicated generally by the reference numeral 35. The stethoscope 35 comprises the usual flexible ear tubes 36 having ear plugs 38 attached to the free ends thereof. The ear tubes 36 are connected to a bell-shaped hollow head 40.

The head 49 is closed adjacent the bottom thereof by a circular bottom wall 42. The wall 42 may be formed with a pair of openings 44 through which may be positioned a pair of headed rivets 46. Secured to the rivets 46 is a switch plate 48 on which is mounted one contact 50 of the switch 12. A pair of coil springs such as 52 may be coiled about the rivets 46 and is adapted to normally urge the switch plate 48 outwardly to maintain the switch 12 in the open condition indicated. The switch plate 48 may likewise be circular and approximately the same size as the bottom wall 42, thereby substantially concealing and protecting the switch 12.

The interior of the head 40 may be divided into an upper chamber 54 and a lower chamber 56 by a partition 58. The transducer 28 may be mounted in the upper chamber 54 and supported on the partition 58. It will thus be apparent that the sounds produced by the transducer 23 are transmitted directly through the ear tubes 36 where they are audible to the user of the stethoscope.

The remaining elements of the circuit 10 may be mounted in the lower chamber 56 in any suitable manner. Thus, for example, the second contact 60 of the switch 12 may comprise one leg of a channel-shaped conductor 62 which is mounted as indicated on the bottom wall 42. The conductor 62 may also include a cup-shaped retainer 64 for removably supporting the battery 14. A conductor strip 66 may be secured to the bottom of partition 58 in electrical contact with the transducer 28 and the battery 14. The transistors TR1 and TR2 may be connected to the strip 66 as indicated. The resistors R-l, R-2 and R-3 and the condensers C1 and C2 may likewise be mounted in any convenient manner (not shown) in the lower chamber 56. Completing the circuit 10 may be a wire conductor 68 which passes through an opening 70 in the bottom wall 42 and electrically connects the contact 50 and the conductor strip 66.

To operate the stethoscope 35, it is simply necessary for the user thereof to insert the ear plugs 38 into his ears and then press the head 40 against any object such as a doll or the like. Upon the closing of the switch 12, the user immediately hears the simulated heartbeat which is produced as described above.

From the above description and drawings, it should be apparent that I have provided a novel toy stethoscope which permits the user thereof to impart a life-like heartbeat to otherwise inanimate objects such as dolls. The stethoscope employs a novel transistorized circuit which realistically simulates the human heartbeat. The entire circuit may be contained in a stethoscope head of average size and the entire toy is most rugged and dependable in operation. In addition the toy may be inexpensively fabricated and maintained, and yet is most amusing and educational to the user thereof.

It is believed that my invention, including its mode of construction and operation and many of its advantages, should be understood from the foregoing without further description, and it should be manifest that while a specific arrangement and preferred embodiment of the invention have been shown and described for illustrative purposes, the details are nevertheless capable of wide variation within the purview of the invention, as defined in the appended claims.

What I claim and desire to secure by Letters Patent is:

l. A toy stethoscope comprising a head, an audio frequency oscillator mounted in said head, means driven by the oscillator output to produce sound in said stethoscope, and switch means for activating said oscillator. said switch means being biased to open condition and being closeable by pressing said stethoscope against an object.

2. A toy stethoscope comprising an ear tube, a housing connected to the ear tube and adapted to be placed against an object, an audio oscillator including a battery, a speaker electrically connected to said audio oscillator and switch means, all contained in said housing, said switch means operable to activate said audio oscillator when said housing is placed against an object.

3. The toy stethoscope of claim 2 in which said oscillator comprises a multivibrator having semi-conductor amplifiers connected and arranged to produce an output pulse having a heartbeat simulating rate.

4. The toy stethoscope of claim 3 in which said speaker is constructed to convert the said output pulse into a doubled sound pulse.

5. A toy stethoscope comprising a pair of ear tubes, a head connecting said ear tubes, an electronic circuit positioned in said head for simulating a heartbeat, a switch for selectively activating said circuit disposed in the free end of said head, and means normally biasing said switch to open condition, said switch adapted to be closed against said bias when said head is pressed against an object.

6. The toy stethoscope of claim 5 in which said circuit includes a replaceable dry cell battery, a pair of transistors, three resistors, a pair of condensers and a transducer,

said electrical components being arranged so that said References Cited in the file of this patent transducer realistically simulates a human heartbeat.

7. A toy stethoscope comprising a pair of flexible ear UNITED STATES PATENTS tubes, a hollow head connecting said ear tubes, an elec- 1,332,402 Langer v, 17, 1931 tronic audio frequency oscillator of circuit constants to 6 2 715 29 pettit A 1 1955 simulate a heartbeat positioned in said head, means for 2,794,298 Mason June 4, 1957 energizing said circuit including a source of electrical 2954 642 Jackson Oct 4, 1960 power and a switch to close the circuit for applying said 2957273 Hughes et 31 0st 25 1960 power to said oscillator, a switch actuating plate connected to the free end of said head, and spring means nor- 10 FOREIGN PATENTS mally urging said switch actuating plate outwardly to maintain said switch in open condition, said switch being closeable when said head is pressed against an object.

465,817 Great Britain 1937 

